This invention relates to transverse or cross flow blowers. More particularly, this invention relates to a reversing means for accomplishing flow reversal of the working fluid, e.g. air, in such blowers without the necessity of reversing the impeller direction.
Transverse or cross flow blowers typically have a drum type impeller with forward, curved blades mounted thereon. The impeller, or rotor, is closed at both ends and mounted on a shaft. By rotating the shaft within a housing having an inlet, an outlet, and directing walls, air or other working fluid is pulled in through the inlet across the impeller and is expelled through the outlet. Research in the early 1950's, primarily in Germany, led to the discovery that flow within the impeller itself is characterized by the formation of a vortex which is eccentric to the axis of rotation of the impeller. This vortex is controlled by the shape and position of the shroud or wall adjacent the impeller. The vortex may be thought of as a seal which prevents flow carried around in the direction of rotation of the impeller from being returned to the inlet.
Transverse or cross flow fans or blowers have been found to be extremely useful, and have replaced axial flow fans or blowers in numerous applications. They have the advantage of being relatively thin, and are therefore suitable for use in confined spaces such as in refrigerated food display cases and domestic refrigerators. One disadvantage that these cross flow blowers possess is the inability to achieve fluid flow reversal in a practical manner. If flow reversal of the conventional cross flow blower is to be achieved, one approach is to merely reverse the direction of rotation of a motor driving the impeller. However, this is not satisfactory since the impeller blades are curved in the forward flow direction. Another approach would be to manually remove the impeller and turn it end for end while at the same time reversing the motor rotation direction. However, this is a time consuming and laborious task and does not allow for quick changes of flow direction required in certain applications.
One of the applications where such transverse flow fans or blowers are desired to be used is in the earthmoving and material handling equipment field. Here, engines are typically cooled by means of water cooling systems which utilize radiators. A transverse flow blower may be used to augment the cooling of a radiator. However, in the dust filled environment in which this type of equipment operates, the radiator cores frequently become clogged with dirt and consequently the cooling effect reduced to a dangerously low level. At this point the radiator core must be cleaned, usually by hand.
The present invention provides a reversing means for reversing a transverse cross flow blower without the necessity of reversing impeller rotation direction. Thus, if a radiator core with which the blower is used is clogged with dirt, it may be easily cleaned when flow direction is reversed. The invention includes the use of power means for rotating the blower housing 180.degree. so that the flow direction is reversed by reversing inlet and outlet positions. In an alternate embodiment, louvers or vanes which form a shroud or volute wall adjacent the impeller are moved so as to change the vortex flow characteristics of the impeller and thereby accomplish flow reversal without the necessity of reversing the impeller direction itself.